The absence of a widely accepted commercially available method to measure glomerular filtration rate (GFR) in animal models and in the clinic has had profoundly negative effects on (i) developing methods and drugs for treating kidney disease, (ii) accurately assessing kidney transplant recipients and donors, (iii) calibrating drug dosing in the young and elderly, (iv) minimizing nephrotoxicity in the drug development process, and (v) accurately assessing nephrotoxicity in the clinical setting. Inulin is the gold standard for measuring GFR. A sensitive, specific and easy assay to measure inulin is most likely to be accepted for general research, clinical research, and clinical applications. A diagnostic test for inulin using immunoassay techniques to measure its clearance from the kidney offers a unique opportunity for a needed technology and an analytical tool superior to all current methods. We have raised polyclonal antisera to inulin and propose to develop a set of reagents that demonstrate the feasibility of measuring inulin using immunoassay. An inulin immunoassay avoids the shortcomings of other inulin assays and is easy to perform, cost effective, highly specific, and far more sensitive than currently available inulin assays. We anticipate that an immunoassay for inulin can be produced wherein all the reagents are stable, the lower limit of detection of inulin is less than 30ng/ml, the specificity of the antibody for inulin allows discrimination between all common sugars and polysaccharides (both endogenous, synthetic, and botanical), the antibody titer is greater than 10,000, and the assay can be completed within 75 minutes. All of these criteria are necessary for the development of an automated assay for inulin and the commercialization of this assay. Phase II will demonstrate the application of the reagents to measuring GFR values in animal models. PUBLIC HEALTH RELEVANCE: The project will further develop a diagnostic test to measure kidney function. The test will utilize well-known and widely available analytical technology and will utilize the "gold standard" for the measure of kidney function. Therefore, this test will be able to quickly enter the market-place.